JP2003145010A - Coating method, extrusion coating apparatus and method of removing stripe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating method by which the initial stripe does not occur and a method of removing the stripe when it occurs in the application of a coating liquid having >=0.1 Pas viscosity. SOLUTION: When the coating liquid is applied on a belt-like supporting body using an extrusion type die coater for supplying the coating liquid to the belt-like supporting body having a coating position held from the opposite surface of the coating position by a back up roll and continuously transported from the upstream to the downstream, the extrusion type die coater moves at a moving speed from the stand-by position to the coating position at 1-110% of the traveling speed of the belt-like supporting body in the start-up of the coating.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a coating method and an extrusion coating apparatus.

[0002]

2. Description of the Related Art An extrusion type die coater (also called a die coater) can form a high quality coating film even in a high speed range. There is a drawback that foreign matter adhered to the body) is easily caught between the support and the coater lip to generate streaks in the flow direction of the support. When the coating is not applied, that is, when the coater lip surface of the die coater is separated from the support, the coating liquid on the coater lip surface that is exposed to air tends to dry and scum is generated. Many muscle defects tend to occur.

As an attempt to prevent the occurrence of coating streaks at the start of coating or the restart of coating, Japanese Patent No. 260 has been proposed.
As described in No. 1365, a method has been devised in which a die coater and a support are brought close to each other or brought into contact with each other at a small wrap angle, and then the coating liquid is discharged from the die coater, and then wrapping is performed up to a specified wrap angle. There is. However, if the discharge is started in a state where there is a gap between the die coater and the support, a very thick coating film is formed, so that the coating film cannot be completely dried or the support is often broken. Further, when the die coater and the support are brought into contact with each other in a dry state, both the support and the die coater are damaged, which promotes the generation of streaks.

Further, Japanese Patent No. 2520733 describes a method of starting coating by inserting a thin plate-like material between the die coater and the support at the start of coating or by applying air for a short time. Even with this method, a thick coating film is locally formed, so that there is no fear of insufficient drying or breakage of the support.

When the extrusion die coater is moved from the standby position to the coating position, there is a region where coating is unstable (coating cannot be performed). In this unstable region, the coating is performed while entraining air, and at this time, a small wavy unevenness is generated on the coating surface, and streaks are generated on the entire surface from the small wavy portion. In particular, the viscosity of the coating solution is 0.1
It often occurs when applying a material of Pa · s or more.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a coating method in which a leading streak does not occur when a coating liquid having a viscosity of 0.1 Pa · s or more is applied by an extrusion coating apparatus, and a streak when the leading streak occurs. It is to provide a removal method.

[0007]

The above objects of the present invention have been achieved by the following constitutions.

1. The coating position is held from the opposite side of the coating by the back roll, and the coating liquid is applied to the belt-shaped support using an extrusion type die coater that supplies the coating liquid to the belt-shaped support that is continuously conveyed from upstream to downstream. When coating, the extrusion type die coater is characterized in that the moving speed from the standby position to the coating position moves at a speed of 1 to 110% of the transport speed of the strip-shaped support to start the coating. Application method by device.

2. The extrusion type die coater can change the moving speed from the standby position to the coating position, and the moving speed between the coating position and 5 mm before the coating position moves at a speed of 1 to 110% of the conveyance speed of the belt-shaped support. Then, the coating is started, and the coating method according to the above item 1.

3. 3. The coating method according to 1 or 2 above, wherein the viscosity of the coating liquid is 0.1 Pa · s or more.

4. The coating position is held from the opposite side of the coating by the back roll, and the coating liquid is applied to the belt-shaped support using an extrusion type die coater that supplies the coating liquid to the belt-shaped support that is continuously conveyed from upstream to downstream. At the time of coating, the extrusion type die coater can change the moving speed from the standby position to the coating position, and this moving speed changes from the speed command signal of the transfer speed of the strip-shaped support to the die coater moving speed signal. A coating start method for an extrusion coating apparatus, wherein the transfer speed of the belt-shaped support is converted and the moving speed of the die coater is linked.

5. The coating position is held from the opposite side of the coating by the back roll, and the coating liquid is applied to the belt-shaped support using an extrusion type die coater that supplies the coating liquid to the belt-shaped support that is continuously conveyed from upstream to downstream. At the time of coating, the extrusion type die coater can change the moving speed from the standby position to the coating position, and this moving speed changes from the speed command signal of the transfer speed of the strip-shaped support to the die coater moving speed signal. An extrusion coating apparatus in which the transfer speed of the belt-shaped support is converted and the moving speed of the die coater is linked.

6. The coating position is held from the opposite side of the coating by the back roll, and the coating liquid is applied to the belt-shaped support using an extrusion type die coater that supplies the coating liquid to the belt-shaped support that is continuously conveyed from upstream to downstream. At the time of coating, the extrusion die coater moves from the standby position to the coating position, and after the liquid has been applied, a stick is put in the gap between the coater lip and the support and moved in the width direction of the support. Method for removing streaks in a rouge application device.

7. The coating position is held from the opposite side of the coating by the back roll, and the coating liquid is applied to the belt-shaped support using an extrusion type die coater that supplies the coating liquid to the belt-shaped support that is continuously conveyed from upstream to downstream. At the time of coating, the extrusion die coater is moved from the standby position to the coating position, and at the same time when the liquid is applied, a stick is put in the gap between the coater lip and the support and moved in the width direction of the support. A method for removing streaks in an extrusion coating device.

The present invention will be described in more detail. In the present invention, the upstream side refers to the side on which the strip-shaped support is fed out based on the extrusion type die coater, and refers to the side opposite to the downstream side.

The extrusion coating apparatus is composed of a so-called die coater for supplying a coating liquid to form a coating liquid film uniformly on the support and a back roll for uniformly holding the surface of the support continuously running. ing. The coating method using the extrusion coating device is to discharge the coating liquid from the slit of the die coater to form a bead (liquid puddle) in the gap between the part called the coater lip and the surface of the continuously running support held by the back roll. The die coater combines two or more blocks, a supply port for supplying the coating liquid, a manifold for temporarily storing the supplied coating liquid in the width direction, and a uniform coating liquid from the manifold. This is a coating method that has a slit for discharging and enables single-layer to multi-layer coating depending on the number of combinations of blocks.

Before starting coating with the extrusion coating apparatus, various preparatory works such as slit cleaning of the die coater and cleaning of the coater lip are performed. Further, air removal in the liquid supply path and replacement when the type of coating liquid is changed are also performed. After such preparatory work, the coating liquid is caused to flow out from the slit of the die coater at a specified flow rate for coating, and the preparation for coating is completed, and then the coating operation is started. Many streak defects tend to occur at the start of coating or the restart of coating in the coating operation. In particular, the viscosity of the coating liquid is 0.1 Pa
It often occurs when applying s or more.

In the present invention, the viscosity of the coating liquid is 0.1 Pa · s.
It can be preferably used when applying the above,
It is effective for a coating liquid having a viscosity of 0.1 to 7 Pa · s, particularly 0.1 to 5 Pa · s.

As a method of eliminating the leading streaks and applying quickly, the moving speed of the die coater is adjusted, and the moving speed is moved at a speed equal to or higher than the applying speed, so that the occurrence of streaks can be suppressed. It was It was also found that streaks can be suppressed if the moving speed from 5 to 10 mm before the coating position is equal to or higher than the coating speed.

In addition, streak is generated in the leading streak when a streak is generated from a small wavy portion, foreign matter or a dripping state of the coating liquid between the coater lip surface or between the coater lip and the support. In this case, after the liquid is attached,
By putting a stick in the gap between the coater lip and the support and moving it in the width direction of the support, or by putting a stick in the gap between the coater lip and the support and moving it in the width direction of the support at the same time with the liquid. When the leading streak occurs, the streak is removed.

Next, the case of inserting a stick and the occurrence of streaks will be described with reference to the drawings. FIG. 1 is a perspective view when a stick is inserted. Support 1 is back roll 3
The coating liquid (not shown) is applied by the die coater 4 to form the coated support 2. After getting liquid
The stick 5 is inserted into the gap between the coater lip 6 and the support 1 as shown in the figure to remove streaks. FIG. 2 is a cross-sectional view when the stick 5 is inserted.

As the stick 5 to be inserted into the portion between the coater lip 6 and the support 1, the coater lip 6 and the corner portion of the coater lip 6 can be rubbed, and the excess coating liquid on the portion can be removed. The tip is thin,
A blade may be used, but a blade having a sponge or non-woven fabric attached thereto is preferable. FIG. 3A shows a cross-sectional view of inserting the stick 5 having a sponge on the tip, and FIG. 3B shows a cross-sectional view of inserting the stick 5 having a blade at the tip.

In FIG. 4 (a), the streak generated on the entire surface of the coating surface 7 when the coating speed of the extrusion type die coater moves from the standby position to the coating position at a speed not higher than the transporting speed of the support and coating is started. Indicates. On the other hand, when the moving speed of the extrusion type die coater is equal to or higher than the coating speed, the coating surface 7 becomes uniform as shown in FIG.

[0024]

Example 1 Polyvinyl butyral was dissolved in methyl ethyl ketone to prepare coating solutions 1 to 4 having different solid content concentrations. When the viscosities of these coating solutions at 25 ° C. were measured with a B type viscometer, the viscosities shown in Table 1 were obtained.

[0025]

[Table 1]

This coating solution was discharged after adjusting the flow rate supplied to the slit by various die coaters so as to obtain a target coating film thickness, and 100 μm supported by a back roll.
m PET support. Back roll has an outer diameter of 3
A metal roll with a chrome plating surface treatment of 00 mm and a face length of 1300 mm, with a coating width of 1000 mm.
And 100 m under the conditions shown in Table 3. The moving speed of the die coater is a value 5 mm before the coating position. Table 3 shows the results of the streak removing means using a stick having a sponge on the tip immediately after and simultaneously with the application.

[0027]

[Table 2]

[0028]

[Table 3]

From Table 2, it can be seen that Samples 1 to 8 to which the coating method of the present invention is applied have no leading stripes as compared with Comparative Samples 9 to 16. Further, from Table 3, the samples 4 and 8 in which several leading streaks are generated in Table 2 and the samples 9 to 16 in which leading streaks are generated on the entire surface are shown in Table 1 as the samples subjected to the streak removing means by the stick of the present invention. Even though the coating conditions are the same,
It can be seen that there is no leading streak at all and it is an excellent coating method.

[0030]

According to the present invention, there are provided a coating method which does not cause leading streaks when a coating liquid having a viscosity of 0.1 Pa · s or more is applied by an extrusion coating apparatus, and a streak removing method when the leading streaks occur. Can be done.

[Brief description of drawings]

FIG. 1 is a perspective view of a stick inserted into a gap between a coater lip and a support.

FIG. 2 is a sectional view when a stick is inserted into a gap between a coater lip and a support.

FIG. 3 is a cross-sectional view when a stick is inserted when the stick shape is changed.

FIG. 4 is a diagram showing a state of a coating surface when a moving speed of an extrusion type die coater is changed.

[Explanation of symbols]

1 support 2 Pre-coated support 3 back rolls 4 die coater 5 sticks 6 coater lip 7 Application surface

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03C 1/498 G03C 1/498 1/74 351 1/74 351 F term (reference) 2H023 EA03 2H123 AB00 AB03 AB23 AB23 AB28 BC00 BC01 CB00 CB03 4D075 AC04 AC72 AC80 AC88 AC94 DA04 DB48 EA07 EB19 4F041 AA12 AB02 BA06 BA56 CA02 CA22 4F042 AA22 BA27 DD07 DD11 DD19

Claims (7)

[Claims] 1. A strip-shaped support using an extrusion type die coater for supplying a coating liquid to a strip-shaped support whose coating position is held from a surface opposite to the coating by a back roll and which is continuously conveyed from upstream to downstream. When the coating liquid is applied to the extrusion die coater, the moving speed from the standby position to the coating position moves at a rate of 1 to 110% of the transport speed of the strip-shaped support to start the coating. And a coating method using an extrusion coating device. 2. The extrusion type die coater is capable of varying the moving speed from the standby position to the coating position, and the moving speed between the coating position and 5 mm before the coating position is 1 to 110 times the transport speed of the belt-shaped support. The coating method according to claim 1, wherein the coating is started by moving at a rate of%. 3. The coating method according to claim 1, wherein the viscosity of the coating liquid is 0.1 Pa · s or more. 4. A strip-shaped support using an extrusion type die coater for supplying a coating liquid to a strip-shaped support whose coating position is held from a surface opposite to the coating by a back roll and which is continuously conveyed from upstream to downstream. When applying the coating liquid to, the extrusion die coater can change the moving speed from the standby position to the coating position,
This moving speed is converted from a speed command signal of the transfer speed of the belt-shaped support into a die coater moving speed signal, and the transfer speed of the belt-shaped support and the die coater moving speed are interlocked with each other. How to start coating. 5. The strip-shaped support is provided by using an extrusion type die coater for supplying the coating liquid to a strip-shaped support whose coating position is held from a surface opposite to the coating by a back roll and which is continuously conveyed from upstream to downstream. When applying the coating liquid to, the extrusion die coater can change the moving speed from the standby position to the coating position,
An extrusion coating apparatus characterized in that the moving speed is converted from a speed command signal of the transfer speed of the belt-like support into a die coater moving speed signal, and the transfer speed of the belt-like support and the die coater moving speed are interlocked. 6. A strip-shaped support using an extrusion type die coater for supplying a coating liquid to a strip-shaped support whose coating position is held from a surface opposite to the coating by a back roll and which is continuously conveyed from upstream to downstream. When applying the coating liquid to, the extrusion type die coater moves from the standby position to the coating position, and after the liquid is attached, a stick is put in the gap between the coater lip and the support and moved in the width direction of the support. A method for removing streaks in an extrusion coating apparatus, which comprises: 7. A strip-shaped support using an extrusion type die coater for supplying a coating solution to a strip-shaped support whose coating position is held from a surface opposite to the coating by a back roll and which is continuously conveyed from upstream to downstream. When the coating liquid is applied to, the extrusion die coater moves from the standby position to the coating position, and at the same time as the liquid is attached, a stick is put in the gap between the coater lip and the support and moved in the width direction of the support. A method for removing streaks in an extrusion coating apparatus, which is characterized by the above.